This invention relates to the melting of glass, and more particularly to improvements in formulating glass batch mixtures to be fed to a melting furnace so as to achieve better energy efficiency in the operation of the furnace.
Glass batch materials are usually fed to a glass melting furnace in a finely divided state. The finer portions of the batch can become entrained in the combustion gas stream and can be carried out of the furnace by the exhaust gas stream. Portions of this entrained dust can become deposited in the regenerator chambers or other portions of the exhaust gas passageways. Accumulations of these deposits can restrict the flows therethrough which negatively affects the efficiency with which the furnace operates and may require costly maintenance to alleviate the pluggage. For these and other reasons it is common practice in the glass industry to suppress dusting of the glass batch by wetting the glass batch prior to its being fed to the furnace. The most commonly used wetting agent is water, although sometimes caustic soda solutions are employed. Sodium silicate solutions have also been suggested as wetting agents (U.S. Pat. No. 2,975,555). The presence of water in the batch, however, is detrimental to the efficiency of the melting operation because vaporization of the water in the furnace consumes a portion of the energy being supplied to the furnace. It would be desirable to provide wetting of glass batch without incurring an energy penalty.
A sulfur source material, usually a sulfate such as salt cake (Na.sub.2 SO.sub.4) or gypsum (CaSO.sub.4), is conventionally included in glass batch formulas to aid in the melting and refining of the glass. Solid carbonaceous materials such as powdered coal are also sometimes included and are known to assist the action of the sulfur compounds. However, use of unnecessarily large amounts of sulfur or overly vigorous activation by carbon can be wasteful and can lead to undesirable amounts of sulfurous emissions from the melting furnace. Accordingly, the glass industry has sought more effective wasy to utilize sulfur as a glass melting aid (see, for example, U.S. Pat. Nos. 4,138,235 and 4,270,945).